The present invention relates to the positioning of pre-cut blank sheet materials prior to press forming between die halves, and, more particularly, to an apparatus and related method for positioning irregular blanks into aligned position with respect to a die half.
Prior to fabricating formed containers, such as disposable food service plates made of paperboard, by pressing a pre-cut blank between forming dies into the desired shape, it is important to position the blanks in aligned position with respect to the female die half. The usual press forming process is automated and can be operated in a gravity-feed mode in which a blank is allowed to enter the press or die set, is aligned by means including a drawpad in a position relative to the female die half, is press formed into the finished product and then ejected or dropped from the die. The next blank is allowed to enter and the press forming cycle is repeated. Proper alignment of the blank is essential to press form the blank into a finished product having the proper shape and other characteristics such as structural integrity. While simple stationary alignment or guide means are usually sufficient to enable square, rectangular or circular shaped blanks to self-align as they enter the press, blanks having irregular shapes, such as an ellipse, frequently become misaligned which can result in a defective or non-uniform finished product. Included among the problems which result from the inability of irregular shaped blanks to self-align, prior to press forming, are finished products with unevenly shaped outer edges, and which do not stack uniformly.
In providing an apparatus for moving an irregular blank into aligned position relative to a die half, it is important to provide for different drawpads and die halves associated with the various sizes and shapes of the finished product. It is also important to provide alignment means for moving an irregular blank from an initial misaligned position into an aligned position with respect to the major and minor axes of a die half and for holding the blanks in the aligned position upon mating of both die halves. Further, it is important that the alignment means not interfere with the ejection of the finished product from between the die halves after pressing, nor with the insertion of new blanks into position prior to pressing.